Efficient general quantum computer central processing unit and control method thereof

Abstract

The invention provides a high-efficiency general quantum computer central processing unit. The high-efficiency general quantum computer central processing unit is constructed by connecting n quantum bits together through n LC harmonic oscillators which are distributed in a radiation cluster shape, wherein each LC harmonic oscillator has the same inherent frequency, and each LC harmonic oscillator comprises a capacitor and an inductor which are connected with each other; the frequency of each quantum bit is adjustable, and the quantum bits are directly connected to the same point through an inductor of the connected LC harmonic oscillator after being connected with a capacitor of one LC harmonic oscillator; coupling interaction between the quantum bits is achieved through collective harmonic oscillator modules of the n LC harmonic oscillators, and coupling connection or disconnection between the quantum bits is controlled by adjusting the detuning amount between the frequency of the quantum bits and the inherent frequency of the LC harmonic oscillators. By implementing the quantum computer, the problem that a quantum computer in a latticed connection form needs a large number of quantum bits can be avoided, high-efficiency coupling on-off operation between any quantum bits can be realized, and commercial difficulty and cost are reduced.

Description

Technical Field

[0001] The present invention relates to the field of quantum information technology, and particularly to an efficient and general quantum computer central processing unit and a method for manipulating the same. Background Art

[0002] Due to its huge potential application value, quantum computers have attracted the competing research of governments, many technology companies and research institutions in various countries and some progress has been made. However, the practical progress achieved so far is limited to special-purpose quantum computers for implementing certain specific tasks, which are characterized in that the coupling operation between qubits is realized by nearest-neighbor interaction, resulting in the need for a huge number of qubits to perform quantum computing.

[0003] At present, there are still some key problems to be solved in realizing a general-purpose quantum computing that can efficiently utilize qubits commercially, especially the high-efficiency connection and coupling on / off between qubits. In the prior art, the qubit connection forms include a grid-like connection form between nearest-neighbor qubits and an efficient connection and coupling form in which all qubits are directly connected to each other; in the former, all qubits are connected by nearest neighbors, so it is more troublesome to realize the coupling between non-nearest-neighbor qubits, making this kind of quantum computer require a huge number of qubits to perform quantum computing tasks; in the latter, due to the problems such as the effective coupling on / off between qubits being difficult to control and the serious crosstalk effect between qubits not being solved, it has only been explored and experimented in some systems with a small number of qubits, far from meeting the requirements of a commercially available general-purpose quantum computer.

[0004] For the above reasons, finding a quantum computer implementation scheme that can efficiently connect and couple on / off between any qubits with high fidelity has become the key and core issue in manufacturing a general-purpose quantum computer. Therefore, it is necessary to design a new qubit connection form for quantum computers, which can not only fundamentally reduce the number of qubits to avoid the problem of a huge number of qubits required by the grid-like connection form, but also simply realize the high-efficiency coupling on / off operation between any qubits, significantly reducing the difficulty and cost of realizing a commercially available general-purpose quantum computer. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide an efficient and general quantum computer central processing unit and a method for manipulating the same, which can not only fundamentally reduce the number of qubits to avoid the problem of a huge number of qubits required by a quantum computer with a grid-like connection form, but also simply realize the high-efficiency coupling on / off operation between any qubits, significantly reducing the difficulty and cost of realizing a commercially available general-purpose quantum computer.

[0006] To solve the above technical problems, an embodiment of the present invention provides an efficient and general quantum computer central processing unit, which is constructed by connecting n quantum bits together through n LC resonators distributed in a radiation cluster; n is a positive integer greater than 1;

[0007] Each LC resonator has the same natural frequency, and each of them includes a capacitor and an inductor connected to each other;

[0008] The frequency of each quantum bit is adjustable, and after each of them is connected to the capacitor of an LC resonator, it is directly connected to the same point through the inductor of the connected LC resonator;

[0009] Among them, the coupling interaction between the quantum bits is realized through the collective resonator mode of the n LC resonators, and the coupling connection or disconnection between the quantum bits is controlled by respectively adjusting the detuning amount between the frequency of each quantum bit and the natural frequency of the LC resonator; the detuning amount is the absolute value of the difference between the frequency of the quantum bit and the natural frequency of the LC resonator.

[0010] Among them, if the detuning amount between the frequency of each quantum bit before adjustment and the natural frequency of the LC resonator is greater than the preset first coupling strength, it is determined that all the quantum bits have never been coupled;

[0011] If the detuning amount between the frequency of each quantum bit after adjustment and the natural frequency of the LC resonator is greater than the preset first coupling strength, it is determined that the coupling between all the quantum bits is disconnected.

[0012] Among them, if the detuning amount between the frequency of two or more quantum bits after adjustment and the natural frequency of the LC resonator is greater than the preset third coupling strength and less than the second coupling strength, and the sum of the frequencies of the two or more quantum bits and the natural frequency of the LC resonator is greater than the preset second coupling strength and less than the first coupling strength, it is determined that the coupling between the two or more quantum bits is connected; among them, the first coupling strength is greater than the second coupling strength which is greater than the third coupling strength.

[0013] Among them, the quantum bit is one of a superconducting charge quantum bit, a quantum dot quantum bit and an ion trap quantum bit.

[0014] Among them, when the quantum bit is a superconducting charge quantum bit, the capacitor connected to the inductor is connected in series with the parallel total capacitance of all other capacitors except this capacitor and connected to the superconducting island of the quantum bit to form the total capacitance of the resonator.

[0015] An embodiment of the present invention also provides a method for operating an efficient and general quantum computer central processing unit, which is implemented on the above-mentioned general and efficient quantum computer central processing unit, and the method includes the following steps:

[0016] S1. Determine that all couplings between qubits are disconnected, and initialize the states of all qubits.

[0017] S2. Select the current qubit coupling mode, and based on the selected current qubit coupling mode, determine the qubits to be coupled and connected, and further perform corresponding operations on the qubits to be coupled and connected and the qubits other than them respectively; wherein, the current qubit coupling mode is any pair of two-qubit coupling modes or any set of multi-qubit parallel coupling modes; the operations include external magnetic flux adjustment and gate voltage adjustment.

[0018] S3. After the operations of the selected current qubit coupling mode are completed, determine the next operation type, and based on the next operation type, determine the specific manipulation of each qubit; wherein, the next operation type is one of continuing the next coupling operation, performing single-qubit operations, temporarily saving the results obtained from the previous operations, and the results of the quantum states obtained after a series of operations including joint measurement.

[0019] Wherein, before step S1, there is also a step:

[0020] Adjust the frequencies of each qubit, and make the detuning between the adjusted frequencies of each qubit and the natural frequency of the LC resonator greater than a preset first coupling strength to ensure that all couplings between qubits are disconnected; wherein, each qubit realizes frequency adjustment by adjusting the external magnetic flux and the gate voltage; the number of Cooper pairs induced by the gate voltage of each qubit on the superconducting island satisfies a first predetermined number, and its external magnetic flux is 0.

[0021] Wherein, step S2 specifically includes:

[0022] If the selected current qubit coupling mode is any pair of two-qubit coupling modes, determine the two qubits to be coupled and connected, and adjust the external magnetic fluxes of the two qubits to be coupled so that they have the same effective Josephson energy, so that the detuning between the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset third coupling strength and less than the second coupling strength, and the sum of the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset second coupling strength and less than the first coupling strength, and then keep the external magnetic fluxes of the qubits other than the two qubits to be coupled and connected at 0 and in an idle state; wherein, the detuning is the absolute value of the difference between the frequency of the qubit and the natural frequency of the LC resonator.

[0023] Adjust the gate voltages of all qubits so that the number of Cooper pairs induced by the gate voltages of all qubits on the superconducting island satisfies a second predetermined number. After maintaining the adjusted external magnetic flux and gate voltages for a first time period required for the quantum gate coupling operation, further adjust the external magnetic flux of the qubits to be coupled to 0 and keep the qubits in an idle state.

[0024] Among them, step S2 further includes:

[0025] If the currently selected current qubit coupling mode is any set of parallel coupling modes between multiple qubits, determine the multiple qubits to be coupled and connected, and adjust the external magnetic fluxes of the multiple qubits to be coupled and connected so that the multiple qubits to be coupled and connected all have the same effective Josephson energy, so that the detuning between the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset third coupling strength and less than the second coupling strength, and the sum with the natural frequency of the LC resonator is greater than a preset second coupling strength and less than the first coupling strength. After that, keep the external magnetic fluxes of the qubits other than the multiple qubits to be coupled and connected at 0 and in an idle state;

[0026] Adjust the gate voltages of all qubits so that the number of Cooper pairs induced by the gate voltages of all qubits on the superconducting island satisfies a third predetermined number. After maintaining the adjusted external magnetic flux and gate voltages for a second time period required for the quantum gate coupling operation, further adjust the external magnetic flux of the qubits to be coupled to 0 and keep the qubits in an idle state.

[0027] Among them, the specific steps of step S3 include:

[0028] If the currently selected current operation is to continue the next coupling operation, return to step S2 to continue the operation;

[0029] If the currently selected current operation is to perform a single qubit operation, adjust the external magnetic flux and gate voltage of the qubit according to the operation required by the qubit to be operated, and use the microwave pulse on the XY control line to implement the corresponding single qubit manipulation. At the same time, adjust and maintain the number of Cooper pairs induced by the gate voltages of the qubits other than the qubit to be operated on the superconducting island to satisfy a fourth predetermined number and the external magnetic flux to be 0, and further maintain the adjusted external magnetic flux, gate voltage, and single qubit manipulation within a third time period required for the single qubit operation;

[0030] If the currently selected current operation is to temporarily save the result obtained from the previous operation, adjust the external magnetic fluxes of all qubits to 0, and maintain the adjusted external magnetic flux and gate voltage within a fourth time period required for temporary saving;

[0031] When the currently selected operation is to jointly measure the result of a series of operations on a quantum state, the external magnetic fluxes of each qubit are adjusted to 0, and at the same time, the gate voltages of each qubit are adjusted so that the number of Cooper pairs induced on the superconducting island of each qubit satisfies the fifth predetermined number, and then the quantum state is immediately jointly measured.

[0032] Implementing the embodiments of the present invention has the following beneficial effects:

[0033] 1. The present invention realizes the direct connection between any qubits among all qubits of the central processing unit of a general-purpose and efficient quantum computer. This connection is achieved through LC resonators. The operation of coupling on and off between any qubits can be realized by adjusting the relationship between the frequency of the qubit (completed by adjusting the external magnetic flux) and the natural frequency of the LC resonator, thereby maximizing the manipulation and usage efficiency of the qubits, achieving the highest efficiency of general-purpose quantum computing. At the same time, it can also fundamentally reduce the number of qubits, avoiding the situation where other types of quantum computers with a grid-like distribution require a huge number of qubits, and significantly reducing the difficulty and cost of realizing a commercial general-purpose quantum computer.

[0034] 2. When the external magnetic flux of the qubit in the present invention is 0, it is in an idle state (that is, it is in an idle state without the need for external magnetic flux operation). The coupling between these qubits and between them and the qubits subjected to external magnetic flux operation is disconnected. If it is necessary to turn on the coupling between the qubits, an external magnetic flux is applied to these qubits. Therefore, all qubits only need to be in two states: the maximum frequency state without external magnetic flux and the coupling frequency state with a specific external magnetic flux, that is, only two specific frequencies of the qubits need to be used. Therefore, there is no problem of frequency congestion, which is very convenient for the operation of the quantum computer.

[0035] 3. The present invention only requires two frequency states. Therefore, the frequency of the idle qubit is taken as the maximum value, so that the detuning value formed between the idle frequency of the qubit and the natural frequency of the LC resonator is very easy to be much larger than the interaction strength between the qubit and the collective mode of the resonator (for example: five orders of magnitude larger). Therefore, the error in the rotating wave approximation analysis can be very small, thereby greatly improving the fidelity of quantum computing.

[0036] 4. The present invention can not only realize the coupling between any two qubits, but also realize the parallel coupling operation between multiple qubits, thereby improving the efficiency of general-purpose quantum computing. Description of the Drawings

[0037] To more clearly illustrate the embodiments of the present invention or the prior art solutions, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, obtaining other drawings based on these drawings still falls within the scope of the present invention.

[0038] Figure 1 Schematic diagram of the structure of a high-efficiency and general-purpose quantum computer central processing unit provided by an embodiment of the present invention;

[0039] Figure 2 Electrical structure diagram of a single qubit in a high-efficiency and general-purpose quantum computer central processing unit provided by an embodiment of the present invention;

[0040] Figure 3 Flowchart of a method for operating a high-efficiency and general-purpose quantum computer central processing unit provided by an embodiment of the present invention. Detailed implementation manners

[0041] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings.

[0042] As Figure 1 shown, in an embodiment of the present invention, a high-efficiency and general-purpose quantum computer central processing unit is proposed, which is constructed by connecting n qubits Q in a radiation cluster-like distribution through n LC resonators; n is a positive integer greater than 1, and i = 1, 2,..., n; wherein, i Each LC resonator has the same natural frequency, and each of them includes a capacitor C

[0043] and an inductor L i connected to each other; i ;

[0044] The frequency of each qubit Q i is adjustable, and after each of them is connected to a capacitor C of an LC resonator i and is directly connected to the same point O through the inductor L of the connected LC resonator i ; wherein, the qubit Q i is one of a superconducting charge qubit, a quantum dot qubit, and an ion trap qubit; it should be noted that when the qubit is a superconducting charge qubit, the total capacitance of the LC resonator is composed of the capacitance obtained by connecting in series the parallel capacitance C i of all other capacitors connected to the superconducting island of the qubit and the capacitance C ∑i of the qubit.

[0045] That is, the inductor L of each LC resonatori One end of each inductor L is connected to the same point O i and the other end of each inductor L is respectively connected to one pole of a capacitor C i and the other pole of each capacitor C is connected to a qubit Q i ; i

[0046] At this time, the qubits are coupled to each other through the collective harmonic oscillator mode of n LC harmonic oscillators, and the coupling between the qubits is controlled by adjusting the detuning between the frequency of each qubit Q i and the natural frequency of the LC harmonic oscillator; the detuning is the absolute value of the difference between the frequency of the qubit Q i and the natural frequency of the LC harmonic oscillator. i

[0047] It should be noted that all connecting wires and the inductor L i are implemented by coaxial cables. The qubits are coupled to each other through the common harmonic oscillator mode of all LC harmonic oscillators, so that the on-off of the coupling between the qubits is controlled by the detuning between the frequency of the qubit Q i and the natural frequency of the LC harmonic oscillator. At this time, each qubit Q i can be designed with the same structure, and the frequency of each qubit Q i is adjusted by an external magnetic flux. When the external magnetic flux of the qubit Q i is 0, the corresponding frequency of the qubit Q i is the maximum, and this frequency is much greater than the natural frequency of the LC harmonic oscillator and the preset multiple coupling strengths. i i

[0048] When the detuning between the frequency of the qubit Q i and the natural frequency of the LC harmonic oscillator is greater than the preset first coupling strength, the coupling interaction between this qubit Q i and other qubits Q j is disconnected and in an idle state. When the detuning between the frequencies of two (or more) qubits and the natural frequency of the LC harmonic oscillator is greater than the preset third coupling strength and less than (for example, less than 50 times or more) the second coupling strength (for example, much less), and the sum of the two is greater than the preset second coupling strength and less than (for example, less than 50 times or more) the first coupling strength, these two (or more) qubits are coupled through the collective mode of the LC harmonic oscillator.

[0049] As Figure 2 shown, the Josephson energy of the i-th charge qubit is denoted as

[0050] ​​​​

[0051] is the effective Josephson coupling energy in the qubit, and Φ0 is the external magnetic flux;

[0052] At this time, the Josephson energy can be controlled by the external magnetic flux Φ passing through the superconducting loop of the qubit (implemented by the flux bias line Z). The single qubit operation for each qubit can be implemented by microwave pulses on the XY control line. The XY control line is connected to the superconducting island of the qubit Q through the coupling capacitor C ei and the gate voltage applied to the XY control line is denoted as V Xi with the superconducting island of the qubit Q i . The measurement of each qubit is realized through the coaxial waveguide resonator R. The capacitance between the input end of the resonator and the superconducting island is denoted as C Xi , and the gate voltage applied by the resonator is denoted as V Ri . The superconducting island of each qubit is ensured to have C Ri +C Bi >>C i (C Bi is the Josephson capacitance of the qubit) through a parallel capacitor C Ji , so that the qubit can obtain a relatively long coherence time. The induced charge on the superconducting island of the qubit is controlled by the gate voltage V Ji applied to the gate capacitor C gi connected to the superconducting island. At this time, the capacitance C gi connected to the superconducting island of the qubit is C ∑i =C gi +C Xi +C Ri +C Ji +C Bi .

[0053] For the convenience of operation, the present invention adopts a completely symmetric structure. Among them, the capacitors of the LC oscillators satisfy C i ≡C, (i = 1, 2,..., n), the inductors of the LC oscillators are the same and there is no mutual inductance between them, that is, L ij =Lδ ij , (i, j = 1, 2,..., n), the capacitances connected to the superconducting islands of each qubit are the same, that is, C ∑i ≡C ∑ , i = 1, 2,..., n, and it is denoted as

[0054] Therefore, Figure 1 the Hamiltonian of the qubit system of

[0055]

[0056] Among them, take the currents I of n - 1 harmonic oscillator circuits k (k = 1, 2, …, n - 1) and the phases of n superconducting islands as the generalized coordinates, then the Lagrangian of the system can be described by 2n - 2 canonical variables . The generalized momenta corresponding to the generalized coordinates I k and are respectively The operators corresponding to the generalized coordinates and generalized momenta are respectively denoted as

[0057] For any charge qubit, let: And denote the charge induced by the gate voltage on the superconducting island as

[0058] N gμ = -(C gμ V gμ + C Xμ V Xμ + C Rμ V Rμ ) / 2e(2)

[0059] When each qubit is encoded in the lowest two eigen - energy states, in the subspace Hamiltonian spanned by the eigen - states |0 i > and |1 i (i = 1, 2, …, n.), it can be expressed as: That is:

[0060]

[0061] Among them,

[0062] At this time, adjust the gate voltage to be V gi (i = 1, 2, …, n.) such that when we can get:

[0063]

[0064] At this time,

[0065] Rewrite the generalized coordinates and the corresponding canonical momenta of the LC harmonic oscillator as operators:

[0066]

[0067] Among them, the creation and annihilation operators satisfy the commutation relation: Furthermore, construct the following collective - mode operators of the LC harmonic oscillator with the creation and annihilation operators:

[0068]

[0069] where \(k = 1, 2, \ldots, n - 1\), and

[0070] Then:

[0071] At this time, denote the basic coupling strength unit

[0072] When the detuning between the frequencies of all qubits and the frequency of the LC resonator is greater than the first coupling strength \(10 5 \zeta\), in the rotating wave approximation, the interaction can be neglected. Therefore, the Hamiltonian of the system is approximately:

[0073]

[0074] At this time, the coupling between each qubit is in the off state, and all qubits are in the idle state. That is, if the detuning between the adjusted frequencies of each qubit and the natural frequency of the LC resonator is greater than the first coupling strength, then it is determined that the coupling between all qubits is disconnected. Of course, it can be understood that if the detuning between the frequencies of each qubit before adjustment and the natural frequency of the LC resonator is greater than the first coupling strength, then it is determined that all qubits have never been coupled.

[0075] When the sum of the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than the second coupling strength \(10 3 \zeta\) while being much smaller than the first coupling strength, and the detuning between the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than the third coupling strength \(10\zeta\) but much smaller than the second coupling strength, after removing the high-frequency terms in the rotating wave approximation, the obtained Hamiltonian is:

[0076]

[0077] where \(l \lt n\). In particular, when \(l = 2\), only two qubits (denoted as \(r, s\)) need to be coupled, and the Hamiltonian at this time is:

[0078]

[0079] Under the Schrieffer - Wolff transformation, the effective Hamiltonian is obtained:

[0080]

[0081] At this time, for the coupling connection between the qubits to be coupled, all other qubits except the qubits to be coupled are in the idle state. That is, if the detuning between the adjusted frequencies of two or more qubits and the natural frequency of the LC resonator is greater than the third coupling strength and less than (for example, less than 50 times or more) the second coupling strength, and the sum of the frequencies of these qubits and the natural frequency of the LC resonator is greater than the second coupling strength and less than (for example, less than 50 times or more) the first coupling strength, then the coupling connection between these two qubits is recognized.

[0082] When the LC resonator is initially in the vacuum state, the effective Hamiltonian is:

[0083]

[0084] At this time, when the evolution time reaches π / 4J rs seconds, the universal quantum gate operation between two qubits r and s is achieved.

[0085] Similarly, when the number of qubits to be manipulated is 2 < l < n, under the Schrieffer-Wolff transformation, the effective Hamiltonian is obtained:

[0086]

[0087] When the LC resonator is initially in the vacuum state, the effective Hamiltonian is:

[0088]

[0089] Set J rs ≡ J. When the evolution time reaches π / 4J seconds, the universal quantum gate operation between the multiple qubits to be manipulated pairwise is achieved.

[0090] As Figure 3 shown, in an embodiment of the present invention, a method for manipulating a central processing unit of an efficient universal quantum computer is provided, which is implemented on the universal and efficient quantum computer central processing unit provided in the embodiment of the present invention. The method includes the following steps:

[0091] S1. Determine that all couplings between qubits are disconnected, and initialize the states of all qubits;

[0092] The specific process is as follows. Before step S1, it further includes the steps of adjusting the frequencies of each qubit, and making the detuning amount between the adjusted frequencies of each qubit and the natural frequency of the LC resonator greater than a preset first coupling strength to ensure that the couplings between all qubits are disconnected. Among them, each qubit realizes frequency adjustment by adjusting the external magnetic flux and the gate voltage. The number of Cooper pairs induced by the gate voltage of each qubit on the superconducting island is 1 / 2, and its external magnetic flux is 0.

[0093] For example, when initializing the l-th qubit (l is any one from 1 to n), first adjust the gate voltages of each qubit so that the number of Cooper pairs induced by the gate voltage on the superconducting island satisfies the first predetermined number N gl =-(C gl V gl +C Xl V Xl +C Rl V Rl ) / 2e = 1 / 2, and adjust the external magnetic fluxes of each qubit to 0 (at this time, the qubit frequency is the maximum value), so that the difference between the qubit frequency and the natural frequency of the LC resonator is greater than the first coupling strength to ensure that the couplings between all qubits are in the disconnected state. For the qubits that need to perform single-qubit operations, use the microwave pulses on the XY control line to achieve the corresponding manipulations.

[0094] S2. Select the current qubit coupling mode, and according to the selected current qubit coupling mode, determine the qubits to be coupled and connected, and further perform corresponding operations on the qubits to be coupled and connected and the qubits other than them respectively. Among them, the current qubit coupling mode is any pair of two-qubit coupling modes or any group of multi-qubit parallel coupling modes. The operations include external magnetic flux adjustment and gate voltage adjustment.

[0095] The specific process is as follows. (1) If the selected current qubit coupling mode is any pair of two-qubit coupling modes, determine the two qubits to be coupled and connected, and adjust the external magnetic fluxes of the two qubits to be coupled so that they have the same effective Josephson energy, so that the detuning amount between the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset third coupling strength and less than (for example, less than 50 times or more) the second coupling strength, and the sum with the natural frequency of the LC resonator is greater than the preset second coupling strength and less than (for example, less than 50 times or more) the first coupling strength. Keep the external magnetic fluxes of the qubits other than the two qubits to be coupled and connected at 0 and in the idle state. Among them, the detuning amount is the absolute value of the difference between the qubit frequency and the natural frequency of the LC resonator.

[0096] Adjust the gate voltages of all qubits so that the number of Cooper pairs induced by the gate voltages of all qubits on the superconducting island all satisfy the second predetermined number N gμ = -(C gμ V gμ + C Xμ V Xμ + C Rμ V Rμ ) / 2e = 1 / 2, and wait for the first time period t = π / 4J required to maintain the quantum gate coupling operation with the adjusted external magnetic flux and gate voltage rs After that, further adjust the external magnetic flux of the qubits to be coupled to 0 so that the qubits are in the idle state.

[0097] (2) If the currently selected qubit coupling mode is any set of multi-qubit parallel coupling modes, determine the multiple qubits to be coupled and connected, and adjust the external magnetic fluxes of the multiple qubits to be coupled and connected so that the multiple qubits to be coupled and connected all have the same (or similar) effective Josephson energy, so that the detuning between the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than the preset third coupling strength (10ζ) and less than (for example, less than 50 times or more) the second coupling strength (10 3 ζ), and the sum with the natural frequency of the LC resonator is greater than the preset second coupling strength and less than (for example, less than 50 times or more) the first coupling strength (10 5 ζ). After that, keep the external magnetic fluxes of the qubits other than the multiple qubits to be coupled and connected at 0 and in the idle state;

[0098] Adjust the gate voltages of all qubits so that the number of Cooper pairs induced by the gate voltages of all qubits on the superconducting island all satisfy the third predetermined number N gμ = -(C gμ V gμ + C Xμ V Xμ + C Rμ V Rμ ) / 2e = 1 / 2, and wait for the second time period t = π / 4J required to maintain the quantum gate coupling operation with the adjusted external magnetic flux and gate voltage rs After that, further adjust the external magnetic flux of the qubits to be coupled to 0 and let the qubits be in the idle state

[0099] S3. After the operation of the selected current qubit coupling mode is completed, determine the type of the next operation, and determine the specific manipulation of each qubit according to the type of the next operation; wherein, the type of the next operation is one of continuing the next coupling operation, performing a single qubit operation, temporarily saving the result obtained from the previous operation, and jointly measuring the result of the quantum state obtained after a series of operations.

[0100] The specific process is as follows: (1) If the selected current operation is to continue the next coupling operation, return to step S2 to continue the operation;

[0101] (2) If the selected current operation is to perform a single qubit operation, adjust the external magnetic flux and gate voltage of the qubit to be operated according to the operation required for the qubit to be operated, and use the microwave pulse on the XY control line to implement the corresponding single qubit manipulation. At the same time, adjust and maintain the number of Cooper pairs induced on the superconducting island by the gate voltage of the qubits other than the qubit to be operated to satisfy the fourth predetermined number and the external magnetic flux is 0, and further maintain the adjusted external magnetic flux, gate voltage, and single qubit manipulation for the third time period t = π / 4J required for the single qubit operation rs ;

[0102] (3) If the selected current operation is to temporarily save the result obtained from the previous operation, adjust the external magnetic flux of each qubit to 0, and maintain the adjusted external magnetic flux and gate voltage for the fourth time period t = π / 4J required for temporary saving rs ;

[0103] (4) If the selected current operation is to jointly measure the result of the quantum state obtained after a series of operations, adjust the external magnetic flux of each qubit to 0, and at the same time adjust the gate voltage of each qubit so that the gate voltage of each qubit satisfies that the number of Cooper pairs induced on the superconducting island satisfies the fifth predetermined number and immediately perform a joint measurement on the quantum state.

[0104] Implementing the embodiments of the present invention has the following beneficial effects:

[0105] 1. The present invention realizes the direct connection between any qubits among all the qubits of a general-purpose and efficient quantum computer central processor. This connection is achieved through LC oscillators. The operation of coupling on and off between any two qubits can be realized by adjusting the relationship between the frequency of the qubits (completed by adjusting the external magnetic flux) and the natural frequency of the LC oscillator, thereby maximizing the manipulation and utilization efficiency of the qubits, achieving the highest-efficiency general quantum computing. At the same time, it can also fundamentally reduce the number of qubits, avoiding the situation where other types of quantum computers with a grid-like distribution require a huge number of qubits, and significantly reducing the difficulty and cost of realizing a commercial general-purpose quantum computer.

[0106] 2. When the external magnetic flux of the qubits in the present invention is 0, they are in an idle state (i.e., they are in an idle state without the need for external magnetic flux operation). The coupling between these qubits and between them and the qubits subjected to external magnetic flux operation is disconnected. If it is necessary to turn on the coupling between the qubits, an external magnetic flux is applied to these qubits. Thus, all qubits only need to be in two states: the maximum frequency state without external magnetic flux and the coupling frequency state with a specific external magnetic flux, that is, only two specific frequencies of the qubits need to be used. Therefore, there is no problem of frequency congestion, which is very convenient for the operation of the quantum computer.

[0107] 3. The present invention only requires two frequency states. Therefore, the frequency of the idle qubits is taken as the maximum value, making the detuning value formed between the idle frequency of the qubits and the natural frequency of the LC oscillator easily much larger than the interaction strength between the qubits and the collective mode of the oscillator (for example: five orders of magnitude larger). Thus, the error in the rotating wave approximation analysis can be very small, thereby greatly improving the fidelity of quantum computing.

[0108] 4. The present invention can not only realize the coupling between any two qubits, but also realize the parallel coupling operation among multiple qubits, thereby improving the efficiency of general quantum computing.

[0109] Those of ordinary skill in the art can understand that all or part of the steps of implementing the above-described embodiment method can be completed by instructing relevant hardware through a program. The program can be stored in a computer-readable storage medium, such as ROM / RAM, disk, optical disc, etc.

[0110] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. An efficient and general-purpose central processing unit for a quantum computer, characterized in that, It is constructed by connecting n quantum bits together through n LC resonators distributed in a radiation cluster; n is a positive integer greater than 1; among them, Each LC resonator has the same natural frequency, and each of them includes a capacitor and an inductor connected to each other; The frequency of each quantum bit is adjustable, and after each of them is connected to the capacitor of an LC resonator, they are directly connected to the same point through the inductor of the connected LC resonator; Among them, the coupling interaction between quantum bits is realized through the collective resonator mode of n LC resonators, and the coupling connection or disconnection between quantum bits is controlled by adjusting the detuning amount between the frequency of each quantum bit and the natural frequency of the LC resonator respectively; the detuning amount is the absolute value of the difference between the frequency of the quantum bit and the natural frequency of the LC resonator.

2. The general-purpose high-efficiency quantum computer central processing unit according to claim 1, wherein, If the detuning amounts between the frequencies of all quantum bits before adjustment and the natural frequency of the LC resonator are all greater than the preset first coupling strength, it is determined that all quantum bits have never been coupled; If the detuning amounts between the frequencies of all quantum bits after adjustment and the natural frequency of the LC resonator are all greater than the preset first coupling strength, it is determined that the coupling between all quantum bits is disconnected.

3. The general-purpose high-efficiency central processing unit of a quantum computer according to claim 2, wherein If the detuning amounts between the frequencies of two or more quantum bits after adjustment and the natural frequency of the LC resonator are all greater than the preset third coupling strength and less than the second coupling strength, and the sum of the frequencies of the two or more quantum bits and the natural frequency of the LC resonator is greater than the preset second coupling strength and less than the first coupling strength, it is determined that the coupling between the two or more quantum bits is connected; among them, the first coupling strength is greater than the second coupling strength which is greater than the third coupling strength.

4. The general-purpose and high-efficiency quantum computer central processing unit according to claim 3, wherein, The quantum bit is one of a superconducting charge qubit, a quantum dot qubit, and an ion trap qubit.

5. The general-purpose high-efficiency central processing unit of a quantum computer according to claim 4, characterized in that, When the quantum bit is a superconducting charge qubit, the capacitor connected to the inductor is connected in series with the parallel total capacitance of all other capacitors connected to the superconducting island of the quantum bit except this capacitor to form the total capacitance of the resonator.

6. A method for manipulating a central processing unit of an efficient and general quantum computer, characterized in that, It is implemented on the general-purpose high-efficiency quantum computer central processing unit as described in claim 5, and the method includes the following steps: S1. Determine that the coupling between all quantum bits is disconnected, and initialize the states of all quantum bits; S2. Select the current quantum bit coupling mode, and according to the selected current quantum bit coupling mode, determine the quantum bits to be coupled and connected, and further perform corresponding operations on the quantum bits to be coupled and connected and the quantum bits other than them respectively; among them, the current quantum bit coupling mode is any pair of two-qubit coupling modes or any group of multi-qubit parallel coupling modes; the operations include external magnetic flux adjustment and gate voltage adjustment; S3. After the operations of the selected current quantum bit coupling mode are completed, determine the next operation type, and according to the next operation type, determine the specific manipulation of each quantum bit; among them, the next operation type is one of continuing the next coupling operation, performing a single-qubit operation, temporarily saving the result obtained from the previous operation, and jointly measuring the result of the quantum state obtained after a series of operations.

7. The method for operating a central processing unit of a general-purpose and efficient quantum computer according to claim 6, characterized in that, Before step S1, the method further includes the step of: Adjusting the frequencies of each qubit, and making the detuning amount between the adjusted frequency of each qubit and the natural frequency of the LC resonator greater than a preset first coupling strength, so as to ensure that the couplings between all qubits are disconnected; wherein, each of the qubits realizes frequency adjustment by adjusting the external magnetic flux and the gate voltage; the number of Cooper pairs induced by the gate voltage of each qubit on the superconducting island satisfies a first predetermined number, and its external magnetic flux is 0.

8. The manipulation method of the central processing unit of the general-purpose high-efficiency quantum computer according to claim 7, characterized in that, The specific steps of step S2 include: If the selected current qubit coupling mode is any pair of two-qubit coupling modes, determining the two qubits to be coupled and connected, and adjusting the external magnetic fluxes of the two qubits to be coupled to have the same effective Josephson energy, so that the detuning amount between the frequency of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset third coupling strength and less than the second coupling strength, and the sum of the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset second coupling strength and less than the first coupling strength, and then keeping the external magnetic fluxes of the qubits other than the two qubits to be coupled and connected at 0 and in an idle state; wherein, the detuning amount is the absolute value of the difference between the frequency of the qubit and the natural frequency of the LC resonator. Adjusting the gate voltages of all qubits so that the number of Cooper pairs induced by the gate voltages of all qubits on the superconducting island satisfies a second predetermined number, and after maintaining the adjusted external magnetic fluxes and gate voltages for a first time period required for the quantum gate coupling operation, further adjusting the external magnetic fluxes of the qubits to be coupled to 0 and keeping the qubits in an idle state.

9. The manipulation method of the central processing unit of the general-purpose high-efficiency quantum computer according to claim 8, characterized in that, Step S2 further includes: If the selected current qubit coupling mode is any group of multi-qubit parallel coupling modes, determining the multiple qubits to be coupled and connected, and adjusting the external magnetic fluxes of the multiple qubits to be coupled and connected so that the multiple qubits to be coupled and connected all have the same effective Josephson energy, so that the detuning amount between the frequency of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset third coupling strength and less than the second coupling strength, and the sum of the frequencies of the qubits to be coupled and the natural frequency of the LC resonator is greater than a preset second coupling strength and less than the first coupling strength, and then keeping the external magnetic fluxes of the qubits other than the multiple qubits to be coupled and connected at 0 and in an idle state. Adjusting the gate voltages of all qubits so that the number of Cooper pairs induced by the gate voltages of all qubits on the superconducting island satisfies a third predetermined number, and after maintaining the adjusted external magnetic fluxes and gate voltages for a second time period required for the quantum gate coupling operation, further adjusting the external magnetic fluxes of the qubits to be coupled to 0 and keeping the qubits in an idle state.

10. The manipulation method of the central processing unit of the general-purpose high-efficiency quantum computer according to claim 9, characterized in that, The specific steps of step S3 include: If the selected current operation is to continue the next coupling operation, return to step S2 to continue the operation. When the selected current operation is to perform a single-qubit operation, adjust the external magnetic flux and gate voltage of the qubit according to the operation required for the qubit to be operated, and use the microwave pulse on the XY control line to achieve the corresponding single-qubit manipulation. At the same time, adjust and maintain the number of Cooper pairs induced on the superconducting island by the gate voltage of the qubits other than the qubit to be operated to satisfy the fourth predetermined number and the external magnetic flux to be 0. Further, maintain the adjusted external magnetic flux, gate voltage, and single-qubit manipulation within the third time period required for the single-qubit operation; When the selected current operation is to temporarily save the result obtained from the previous operation, adjust the external magnetic flux of each qubit to be 0, and maintain the adjusted external magnetic flux and gate voltage within the fourth time period required for temporary saving; When the selected current operation is to jointly measure the result of the quantum state obtained after a series of operations, adjust the external magnetic flux of each qubit to be 0. At the same time, adjust the gate voltage of each qubit so that the gate voltage of each qubit satisfies that the number of Cooper pairs induced on the superconducting island satisfies the fifth predetermined number, and immediately perform a joint measurement on the quantum state.

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